President Barack Obama on Wednesday named Caroline Kennedy as US ambassador to Japan, in the biggest foray into public service for John F Kennedy's sole surviving child.

President Barack Obama on Wednesday named Caroline Kennedy as US ambassador to Japan, in the biggest foray into public service for John F Kennedy's sole surviving child.

The former first daughter, who long resisted running for public office, may enter a larger limelight than anytime since her youth as she takes a key diplomatic role.

In an understated rollout to the long rumored nomination, Obama called Kennedy and several nominees to other posts "fine public servants."

"Our nation will be well-served by these individuals, and I look forward to working with them in the months and years to come," he said in a statement.

Kennedy needs confirmation by the Senate, but she has no open critics and the body is led by the Democratic Party that reveres her father.

The 55-year-old, whom many Americans remember as a girl in the White House, was an early and close Obama supporter.

When the then senator was locked in a tough fight for the Democratic presidential nomination against perceived front-runner Hillary Clinton, Kennedy threw her family's prestige behind Obama by calling him "a president like my father."

Kennedy has limited experience in foreign affairs and is not known for her connection to Japan, although her father was injured in World War II's Pacific theater.

The prospect of Kennedy's nomination had already been welcomed by Japan, a close US ally which is accustomed to high-profile US ambassadors.

Previous US ambassadors have included former vice president Walter Mondale, former speaker of the House Tom Foley and former Senate majority leader Howard Baker.

By contrast, Obama's first-term ambassador John Roos -- known primarily as a fund-raiser -- was seen by some Japanese commentators as a sign of a lower US priority on the country. Roos, however, was later praised for handling the round-the-clock US response to the March 2011 tsunami disaster.

If confirmed, Kennedy would be the first woman to take up the post, a feat sure to be noticed in a country that has historically ranked lower than other wealthy nations in terms of women's empowerment.